Followers drop!

I've realized in two of my twitter accounts a considerable drop in follower amount:
* 8.9K -> 8.6K (marketing niche, English language)
* 41.9K -> 41.7K (money niche, Portuguese language)

Have you seen it too? Would it be consequence of ban wave or they are punishing me for "spam or automated actions"?

probably caused by the 0 following phenomene
You can see this via crowdfireapp.com default "not following back" or "recent unfollowers
you will see accounts with a temporary 0 following count.

i was 3 times affected by the total following loss
in all 3 cases twitter requested phone verification
After that the number will climb up to normal but it takes time

In one case the account was connected with an inactive mobile number and twitter support unlocked
my acc 12h after the request. The decreased phase lasted ~ 36 h and i lost more than 3% of my untargeted followers